There is a considerable body of research which finds that schizophrenics engage in elevated levels of violent behavior. Rates of violence among schizophrenics are frequently compared to rates in the general population. Schizophrenics, however, tend to have relatively low socioeconomic status (SES) and, depending on the sampling frame, may tend to be relatively young and male. Schizophrenics also tend to abuse alcohol and drugs. Since low SES, youth, maleness and substance abuse are characteristic attributes of violent offenders, a part of the excess of violence noted for schizophrenics may be related to the methods of sampling in these studies. There are three positions which may be differentiated in understanding the empirical findings of excessive levels of violence among schizophrenics: 1. The findings are due to sampling errors. When proper demographic controls and controls for substance abuse are utilized, the differences will disappear. 2. Generally, schizophrenics are not violent. Only schizophrenics in the midst of an acute episode might commit violent acts. 3. Antisocial behavior, including violence, is a part of the schizophrenia genetic spectrum. We propose to examine these three positions in the context of two cohorts. The first is a total birth cohort of all individuals born between January 1, 1944 and December 31, 1947 in Denmark (N=358,180). Due to the existence of highly accurate national registers, data are available on every arrest for violence and every hospitalization for mental illness that occurred for individuals in this cohort through the age of 44-47 years. This cohort will be utilized to test hypotheses related to the first two positions listed above. Hypotheses related to the third position will be examined in the context of a total cohort of adoptions (The Copenhagen Adoption Cohort) which includes all nonfamilial adoptions (N= 14,427) in Denmark, 1924-1947. Violent offending in the biological parents will be correlated with schizophrenia in the adopted-away offspring.